docs: def config_field_type(field, cls):
      """Validate a config field against a type.
  
      Similar functionality to :func:`validate_field_matches_type` but returns :obj:`honeycomb.defs.ConfigField`
      """
      return defs.ConfigField(lambda _: isinstance(_, cls),
                              lambda: CONFIG_FIELD_TYPE_ERROR.format(field, cls.__name__))